PUBLICATION BIAS IN OBESITY TREATMENT TRIALS

OBJECTIVE: The present investigation examined the extent of publicatio n bias (namely the tendency to publish significant findings and file a way non-significant findings) within the obesity treatment literature. DESIGN: Quantitative literature synthesis of four published meta-anal yses from the obesity treatment literature. Interventions in these stu dies included pharmacological, educational, child, and couples treatme nts. METHODS: To assess publication bias, several regression procedure s (for example weighted least-squares, random-effects multi-level mode ling, and robust regression methods) were used to regress effect sizes onto their standard errors, or proxies thereof, within each of the fo ur meta-analysis. A significant positive beta weight in these analyses signified publication bias. RESULTS: There was evidence for publicati on bias within two of the four published meta-analyses, such that revi ews of published studies were likely to overestimate clinical efficacy . The lack of evidence for publication bias within the two other meta- analyses might have been due to insufficient statistical power rather than the absence of selection bias. CONCLUSIONS: As in other disciplin es, publication bias appears to exist in the obesity treatment literat ure. Suggestions are offered for managing publication bias once identi fied or reducing its likelihood in the first place.